Band alignment at a nonplanar Si/SiO2 interface

The interfacial electronic properties of silicon nanocrystals embedded in a silica matrix are studied using ab initio density-functional theory. We aim to obtain local band edges for a typical nanostructured system, nanocrystals embedded in a surrounding matrix. We compute the spatial variation in the electronic structure for realistic Si nanocrystals with nominal diameters ranging between 0.8 and 1.6 nm, i.e., up to systems with more than 1000 atoms. The evolution of the valence and conduction band edges between Si nanocrystals and amorphous silica along radial directions versus size is presented. Significant differences are found comparing embedded Si nanocrystals and planar Si/SiO2 interfaces.